Traditionally, the manufacture of automobile tires has generated large amounts of vulcanized rubber waste material. When making automobile, truck, and airplane tires, to name a few types of rubber materials made from vulcanized rubber, excess rubber cures on the outside portion of the tire. The inclusion of the excess rubber on the tire is undesirable, consequently it is the practice in the tire industry to grind, sand, or buff the excess rubber off the tire. This action creates waste rubber material generally referred to in the rubber industry as RIS grindings, rubber buffings, or crumb rubber, with the waste rubber material generally disposed of using traditional waste disposal methods, such as burial in a landfill. This is undesirable because landfill space is scarce and disposing of such materials can be expensive.
The waste rubber material is typically disposed of because there are very few known uses for such material as it tends to be of a small dust like size. When the waste rubber material has a small particle size, not only does it have few uses, but it is difficult to handle. The waste rubber material tends to clump together if it is wet, so as to form large clumps of rubber material. If the waste rubber material is dry it tends to dissipate easily. As such, while asphalt production methods often require the addition of vulcanized rubber, especially styrene-butadiene, the inclusion of waste rubber material in the asphalt formation process tends to be undesirable and impractical. The primary problem with using the waste rubber material, in particular rubber tire waste, to form the asphalt is that the asphalt formation process produces faulty asphalt if large clumps of rubber are added to the process and currently the waste rubber material tends to clump into large chunks of rubber. Further, waste rubber material often contains waste material, such as cigarette butts, metal, aluminum cans, and a variety of other types of waste generated in a tire manufacturing facility which can result in the production of faulty asphalt. Thus, it would be desirable to have a method or composition for disposing of waste rubber material in a useful way. It would also be desirable to have a method for using waste rubber material in an asphalt formation process.
It is known to use rubber materials in the formation of asphalt and, in particular, rubber can be used in association with an asphalt formation system owned and marketed by Polyphalt.RTM. of Toronto, Canada. The Polyphalt.RTM. system uses a variety of disposable rubber and plastic materials to form high quality asphalt, with tire rubber being one of the waste materials suitable for use in the Polyphalt.RTM. system. Vulcanized rubber in particular, is generally required for use in the formation of asphalt compositions made according to the Polyphalt.RTM. method. While waste tire rubber is suitable for use in the asphalt formation system, the handling characteristics and size of the waste tire rubber is undesirable. Once again, the waste tire rubber particles tend to stick together to form agglomerated clumps of rubber which means the rubber waste can not be used in the Polyphalt.RTM. asphalt formation system. Thus, while waste rubber is an acceptable type of rubber for use in the Polyphalt.RTM. system, the handling characteristics of the waste rubber make it essentially unavailable for use. As such, it would be desirable to have a method or composition which would allow the easy use of waste rubber in an asphalt formation system.
When asphalt is formed according to the Polyphalt.RTM. system, the method of formation requires the addition of rubber constituents and plastic constituents. Typically, the rubber and plastic constituents are added separately so that the addition of each specific constituent ingredient requires a separate holding device and separate addition step in the asphalt formation process. The requirement of separate pieces of equipment to hold and add the constituent ingredients makes the asphalt formation process more expensive than if the machinery was not required. Thus, it would be desirable to have a method or composition that eliminates the separate addition steps for some of constituent ingredients and that eliminates the need for some pieces of equipment.